A. Technical Field
The present invention pertains generally to image processing, and relates more particularly to embedding and/or extracting data in images.
B. Background of the Invention
The proliferation of computers with increasing computational power has contributed to the growth of digital image processing. Digital images can typically be copied without concern for image degradation. Digital images can also be easily modified, enhanced, and adapted to provide high-quality images that meet a wide range of application requirements. These characteristics of digital images are also sources of concern for owners of images that wish to protect copyrights in the images or that wish to detect and identify sources of unauthorized copying.
In response to these concerns, there have been attempts to develop ways to embed information into digital signals, such as images, that can identify the owner of the digital signal or that can identify the device that was used to produce the digital signal or a copy thereof. In particular, there has been considerable effort to develop ways to embed authenticating information into images to enable subsequent proof of ownership or to enable source tracking for images produced on permanent media such as paper.
Some implementations embedded information that is clearly visible in the images. Although such methods make detection easy, it distorts the original image. Other attempts to make the embedded data more inconspicuous require extraction methods that are time consuming or require extensive computational effort to detect the embedded information. Furthermore, such methods may not reliably extract the embedded information.
What are needed are information embedding techniques that can embed data into a digital signal, such as an image, and can easily and robustly recover the embedded data.